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Thread: Navien

  1. #1
    Join Date
    Feb 2007
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    19

    Navien

    I'm having a Navien CR180 tankless hot water system installed soon.I live in southern Ontario where in the winter the water supply temp is around 40F. I'm concerned the unit will not be able to produce water hot enough for a hot shower or running a dishwasher etc.. I'm getting about 2gpm max from any of my taps. I'm not concerned about having enough for 2 operations at the same time like a shower and running the dishwasher as my water pressure is just too low for that. Thanks for any input.

  2. #2
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    Jul 2009
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    Ontario, Canada
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    Quote Originally Posted by Carzie View Post
    I'm having a Navien CR180 tankless hot water system installed soon.I live in southern Ontario where in the winter the water supply temp is around 40F. I'm concerned the unit will not be able to produce water hot enough for a hot shower or running a dishwasher etc.. I'm getting about 2gpm max from any of my taps. I'm not concerned about having enough for 2 operations at the same time like a shower and running the dishwasher as my water pressure is just too low for that. Thanks for any input.
    The unit should maintain the set temp fairly constant. You may see a decrease in water pressure when more faucets are running, but again the temp should be about the same. I know I experience this with my Rinnai unit. Temp is about the same, but the pressure, especially when incoming water is cold like today, will go down! Maybe have a plumber check to see what the incoming water pressure is coming into your home--the 2gpm that you state seem like you have low-flow water faucets installed..?

  3. #3
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    Dec 2009
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    McCook NE
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    Can you put in a 50 gallon water tank and let it fill the tank before it go into the water heater? At least that way it could reach room temperature after it stands.

  4. #4
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    Jul 2009
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    Quote Originally Posted by Gimmered View Post
    Can you put in a 50 gallon water tank and let it fill the tank before it go into the water heater? At least that way it could reach room temperature after it stands.
    Not sure, but he should get the Navien unit which has a small built in tank within the unit. This way you should have almost instant hot water when the tap is open, and before the hot water is finished in the tank, the main burners will kick on until demand is satisfied, refills the tank, and idles until the next use....

  5. #5
    Join Date
    Jan 2004
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    Lancaster PA
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    If your only tapping 2 gallons a minute. It will have no trouble providing hot water for a shower at a 40 entering water temp.
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  6. #6
    Join Date
    Dec 2003
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    709
    Quote Originally Posted by Gimmered View Post
    Can you put in a 50 gallon water tank and let it fill the tank before it go into the water heater? At least that way it could reach room temperature after it stands.
    I like this Idea if you have the room, you could get a 50 gallon electric water heater and pipe your cold feed to your water heater into it first and then come out of the hot tap into the tankless. You could even have the electric wired up as back up in case the tankless fails. But this way your tankless will always have 50 gallons of room temp water to work with.

  7. #7
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    Dec 2007
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    Cedar Grove, Wi-Sheboygan
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    I to would go the way of a pre-heated water tank and also put in a Taco recirculating water pump so that you will have immediate hot water at any tap in the house, and if your water pressure is to low you can also add a pressure tank like those used on well pumps to increase the incoming water pressure. But on your incoming water line into the house is smaller than 3/4" there is where your problem is to start as most homes should have a minimum 3/4" water line coming into the home. Another solution to increase your water pressure is to build or have someone build you a manifold like those used in radiant floor heat with a main water line coming into the manifold that will equalize the water pressure to all tap in the house no matter how many taps are used at one time.

  8. #8
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    Jan 2004
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    Lancaster PA
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    That 180 can supply 3 GPM at 100°F rise.

    Why does he need a tank heater as a preheat?

    Some what defeats the purpose of a tankless water heater.
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  9. #9
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    Jun 2005
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    Quote Originally Posted by hivacer View Post
    I like this Idea if you have the room, you could get a 50 gallon electric water heater and pipe your cold feed to your water heater into it first and then come out of the hot tap into the tankless. You could even have the electric wired up as back up in case the tankless fails. But this way your tankless will always have 50 gallons of room temp water to work with.
    If the electric portion is disabled, and it is used as a storage tank, wouldn't it take an awful long time for the 40* water in the tank to reach "room temperature" if that tank is insulated? Room temperature, if in a basement, is maybe 65*F- resulting in a ~15* difference...

    My gas fired water heater still has hot water in the tank after 5 days of just a pilot setting (hot being defined as warmer than room temperature)... 110*F water to start and 65* indoor temp is a 45* difference, so heat transfers faster at first.

  10. #10
    Join Date
    Jul 2008
    Location
    Rochester NY
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    That unit has a valve that will restrict flow if it can't deliver delta open. Consider upgrading to the A model, you don't have to run recirc feature, but if it turns out to be an important feature that you DONT have, you'll be unhappier about not having it than the few bucks you spend to have it.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  11. #11
    Join Date
    Oct 2009
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    Finland
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    At least that way it could reach room temperature after it stands.
    Have you ever heard of legionella

  12. #12
    Join Date
    Dec 2003
    Posts
    709
    Quote Originally Posted by -MAKE- View Post
    Have you ever heard of legionella
    legionella would not be anymore of an issue with this setup than it is any any home with tank water heater. Really not an issue at all, the water in this tank is going to be used anytime a hot water tap is used.

  13. #13
    Join Date
    Dec 2003
    Posts
    709
    Quote Originally Posted by neophytes serendipity View Post
    If the electric portion is disabled, and it is used as a storage tank, wouldn't it take an awful long time for the 40* water in the tank to reach "room temperature" if that tank is insulated? Room temperature, if in a basement, is maybe 65*F- resulting in a ~15* difference...

    My gas fired water heater still has hot water in the tank after 5 days of just a pilot setting (hot being defined as warmer than room temperature)... 110*F water to start and 65* indoor temp is a 45* difference, so heat transfers faster at first.
    It probably would take a long time, you would probably have to use the water heater and set the thermostat at its lowest setting to preheat the water.

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